Insectivorous Plants eBook

This eBook from the Gutenberg Project consists of approximately 527 pages of information about Insectivorous Plants.

I was led to investigate the habits and structure of the species of this genus partly from their belonging to the same natural family as Pinguicula, but more especially by Mr. Holland’s statement, that “water insects are often found imprisoned in the bladders,” which he suspects “are destined for the plant to feed on."* The plants which I first received as Utricularia vulgaris from the New Forest in Hampshire and from Cornwall, and which I have chiefly worked on, have been determined by Dr. Hooker to be a very rare British species, the Utricularia neglecta of Lehm.  I subsequently received the true Utricularia vulgaris from Yorkshire.  Since drawing up the following description from my own observations and those of my son, Francis Darwin, an important memoir by Prof.  Cohn

The ‘Quart.  Mag. of the High Wycombe Nat.  Hist.  Soc.’  July 1868, p. 5.  Delpino (’Ult.  Osservaz. sulla Dicogamia,’ &c. 1868-1869, p. 16) also quotes Crouan as having found (1858) crustaceans within the bladders of Utricularia vulgaris.

  I am much indebted to the Rev. H.M.  Wilkinson, of Bistern, for having
  sent me several fine lots of this species from the New Forest.  Mr.
Ralfs was also so kind as to send me living plants of the same species from near Penzance in Cornwall. [page 396]

on Utricularia vulgaris has appeared;* and it has been no small satisfaction to me to find that my account agrees almost completely with that of this distinguished observer.  I will publish my description as it stood before reading that by Prof.  Cohn, adding occasionally some statements on his authority.

Fig. 17. (Utricularia neglecta.) Branch with the divided leaves bearing bladders; about twice enlarged.

Utricularia neglecta.—­The general appearance of a branch (about twice enlarged), with the pinnatifid leaves bearing bladders, is represented in the above sketch (fig. 17).  The leaves continually bifurcate, so that a full-grown one terminates in from twenty to thirty

* ‘Beitrage zur Biologie der Plflanzen’ drittes Heft, 1875. [page 397]

points.  Each point is tipped by a short, straight bristle; and slight notches on the sides of the leaves bear similar bristles.  On both surfaces there are many small papillae, crowned with two hemispherical cells in close contact.  The plants float near the surface of the water, and are quite destitute of roots, even during the earliest period of growth.* They commonly inhabit, as more than one observer has remarked to me, remarkably foul ditches.

The bladders offer the chief point of interest.  There are often two or three on the same divided leaf, generally near the base; though I have seen a single one growing from the stem.  They are supported on short footstalks.  When fully grown, they are nearly 1/10 of an inch (2.54 mm.) in length.  They are translucent, of a green colour, and the walls are formed of two layers of cells.  The exterior

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Insectivorous Plants from Project Gutenberg. Public domain.
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